The present invention relates to a method of making solid plastic bearings and the bearings made thereby which are especially useful in apparatus for washing vehicles.
It is long been a problem keeping bearings used in a moist, water sprayed environment properly maintained and operational. Prior art bearings are generally fabricated from metal and include balls or rollers that must be lubricated to minimize rust, friction and wear. When such bearings are used in a moist environment they must be sealed to prevent water from causing the bearing parts to rust and/or freeze-up.
Car wash equipment places extraordinary demands upon bearings because they are constantly exposed to spraying water and detergent which quickly destroys the lubrication in a bearing if the bearing seal fails. As a result, bearings on car wash equipment must be frequently lubricated and/or replaced to keep the equipment functioning properly. The maintenance is both time consuming and expensive in both manhours and the cost of replacing the bearings. When the bearings are lubricated, grease or oil may be deposited on the strips of finishing material which actually wash, dry, and buff the vechicles. Oil or grease on the finishing material can adversely effect the quality of the wash and may even require the replacement of finishing material.
If a bearing on a critical part of the car wash equipment freezes up, the entire operation may be stopped until the frozen bearing is replaced. If a car wash operation must be stopped on a busy day considerable revenues can be lost.
In car wash equipment shafts frequently move within bearings with an arcuate motion. Such an arcuate motion causes the shaft to bear against a limited portion of the bearing resulting in an uneven bearing surface wear. With ball or roller bearings only a portion of the balls or bearings may actually be subjected to wear. There is no effective way of shifting and holding the bearing elements in a different position to permit other portions of the bearing to wear and extend the useful life of the bearings because the balls or rollers normally revert to their original, worn position.
Segmented high molecular weight plastic bearings are known to be used in hydroelectric power generators. The segmented bearings are formed in quarter sections and are attached to a mounting surface by fasteners which extend through the segment. When the fasteners are tightened in the bearing segments they can squeeze the bearing material and in some cases cause a deformation of the bearing surface. In hydroelectric generators the slight deformation is easily wiped away by the action of the hydroelectric generator shaft due to the tremendous forces exerted thereby. However, such deformation of the bearing surface with lower power drive systems can cause the bearings to seize up or cause undue strain on the drive. In many cases the fasteners which are provided to tighten the bearing segments to a support surface become unfastened due to vibrations. This results in maintenance problems in the field.